The defender was a free agent after his contract with AS Roma expired.
â€śI keep all the Roma teammates in my heart, as Iâ€™ll never forget the city and its fans, who did so much for me. Now I am at Milan and very proud to be part of this club,â€ť he said.
â€śI had seven marvellous years at Roma and itâ€™s partly thanks to them that I grew as a man and a player to earn this opportunity with Milan.
â€śIt was my choice, as I couldâ€™ve joined Real Madrid this summer. In the past I chose Roma ahead of Manchester United. I dreamed of a club like this since childhood and itâ€™s an important shop window, so I can hope to earn a place in the France squad for Euro 2012.â€ť